Vertically adjustable overbed table

ABSTRACT

A vertically adjustable overbed table including a pedestal, a horizontal table top mounted at the top of the pedestal and a horizontal roller-equipped base platform at the lower end of the pedestal. The pedestal includes an upper outer column which telescopes over a lower inner column, and a pair of constant force springs which are mounted within the columns to maintain the telescoping columns in equilibrium. A clutch assembly is mounted within the top of the upper column which includes a rotatable clutch drum, a clutch spring around the clutch drum and a rotatable spool wound with cable, the spool being connected to the clutch drum so that both rotate together. A depending loop is formed at an intermediate portion of the table which engages a pulley wheel at the lower end of a vertical shaft extending below the clutch assembly within the columns. One point of the depending cable is rigidly affixed to the inner column so that the two columns can be moved telescopically only when the cable spool is free to rotate to pay out and take up equal amounts of cable. Lever means are provided for releasing the tension on the clutch spring so that the clutch drum and the spool are free to rotate so that the table can be lowered. An override assembly is also provided in conjunction with the clutch spring which releases the clutch spring tension when a sufficient downward force is placed on the table top so that the table top can be lowered without utilizing the tension releasing lever means. The table top can be raised by exerting an upward force on the table top sufficient to overcome the equilibrium effect of the constant force spring.

United States Patent 1191 Peterson 1 June 24, 1975 VERTICALLY ADJUSTABLEOVERBED TABLE [75] Inventor: Warren J. Peterson, Stevens Point,

Wis.

[73] Assignee: Joerns Furniture Company, Stevens Point, Wis.

[22] Filed: Oct. 24, 1973 [21] Appl. No.: 409,360

[52] U.S. Cl. 108/136; 108/144; 108/146;

[51] Int. Cl A47b 9/02 [58] Field of Search 108/146, 144, 136; 248/162,412, 337, 336

[56] References Cited UNITED STATES PATENTS 3,310.008 3/1967 Aleksa etal. 108/146 3,314,384 4/1967 Mann et 111.... 108/136 3,481,286 12/1969LaMar et al... 108/144 3,504,643 4/1970 Burst et al. 108/146 3,675,5977/1972 Oddsen et al. l08/136 Primary ExaminerMarion Parsons, .lr.

Assistant Examiner-Darrell Marquette Attorney, Agent, or Firm-Price,Heneveld, Huizenga & Cooper [57] ABSTRACT A verticallyadjustable-overbed table including a pedestal, a horizontal table topmounted at the top of the pedestal and a horizontal roller-equipped baseplatform at the lower end of the pedestal. The pedestal includes anupper outer column which telescopes over a lower inner column, and apair of constant force springs which are mounted within the columns tomaintain the telescoping columns in equilibrium. A clutch assembly I ismounted within the top of the upper column which includes a rotatableclutch drum, a clutch spring around the clutch drum and a rotatablespool wound with cable, the spool being connected to the clutch drum sothat both rotate together. A depending loop is-formed at an intermediateportion of the table which engages a pulley wheel at the lower end of avertical shaft extending below the clutch assembly within the columns.One point of the depending cable is rigidly affixed to the inner columnso that the two columns can be moved telescopically only when the cablespool is free to rotate to pay out and take up equal amounts of cable.Lever means are provided for releasing the tension on the clutch springso that the clutch drum and the spool are free to rotate so that thetable can be lowered. An override assembly is also provided inconjunction with the clutch spring which releases the clutch springtension when sufficient downward force is placed on the table top sothat the table top can be lowered without utilizing the tensionreleasing lever means. The table top can be raised by exerting an upwardforce on the table top sufficient to overcome the equilibrium effect ofthe constant force spring.

14 Claims, 12 Drawing Figures VERTICALLY ADJUSTABLE OVERBED TABLEBACKGROUND OF THE INVENTION This invention relates to overbed tables andmore particularly to a vertically adjustable overbed table which can beraised or lowered from either side of the table.

Overbed tables are most often used in hospitals to provide an eating andwork surface for bed-ridden patients. Although some such overbed tablesare rigid structures, many are vertically adjustable so that the patientor nurse can raise or lower the table to the most convenient height.While a variety of mechanisms have been employed in such verticallyadjustable overbed tables, most of such adjustable tables arecrankoperated, spring-biased or a combination of the two. In thecrank-operated tables, the crank must be operated to either raise orlower the table. In the spring-biased tables, a brake lock is generallyemployed in conjunction with a spring. When the brake is released, thetable is free to move either upwardly or downwardly to the desiredposition at which time the brake lock is again engaged. Thedisadvantages of these overbed tables are that the crank-operated tablesare impractical when used with electric powered beds; may offer a hazardto the patient when the bed is elevated, necessitate the rather tediouscranking task, which is sometimes arduous to a weak, sickly patient and,in the case of the spring-biased tables bearing objects of moderate toheavy weight, the danger of the table lowering too quickly when thebrake is released creating the danger of dropping on the patient,spilling food, and the like.

Some more recent overbed tables have employed a combination of crankoperation and spring biasing. For example, in US. Pat. No. 3,504,643, anoverbed table is disclosed which is spring-assisted for raising thetable and which must be cranked to lower the table. Although such anoverbed table minimizes the risk of injury to the patient from the tabledropping on him, it still involves the tedious task of operating thecrank to lower the table. In addition, overbed tables of the spring-biastype now on the market are at best difficult to service and at worse,dangerous to servicing personnel because constant force springs areusually inaccessible inside the telescoping columns, as well as theother mechanism necessary for operation of the table.

Thus, there has been a need for a vertically adjustable overbed tablewhich is easy to raise and lower and which can be safely controlledduring lowering; and a need that such a table can be easily and safelyserviced when necessary.

SUMMARY OF THE INVENTION According to the present invention, there isprovided a vertically adjustable overbed table which does not utilize acrank assembly and which can be easily raised or lowered with nopossibility of being accidentally lowered too quickly even whenoverloaded, thereby eliminating any chance of possible injury to abedridden patient, spilled food and the like. The overbed table of thepresent invention comprises a pedestal column with a horizontal tabletop and a horizontal, rollerequipped base platform, the pedestal beinglocated at the same side of each of the table platform and baseplatform. The pedestal includes'an upper, outer column which telescopesover a lower innercolumn. The height of the table is a function of thedegree to which the lower inner column telescopes into the upper outercolumn.

A spring of the constant force" type is mounted in association with theouter and inner columns to place the telescoping thereof in equilibriumwhen no external force is exerted on the table top. The table top israised by exerting a slight upward force to overcome the telescopingequilibrium produced by the constant force spring.

A clutch assembly which is mounted in the upper portion of the upperouter column controls the lowering of the table. The clutch assembly, inthe preferred embodiment of the invention, comprises a rotatable drumincluding a spool portion and a clutch portion. The clutch portion ofthe drum is engaged by a peripheral helical clutch spring which ismounted and tensioned so that the drum can be freely rotated in onedirection but not in the other direction until the spring tension isovertly released. A cable is wound around the spool portion of the drumwith an intermediate depending loop portion engaging a pulley wheel atthe lower end of a depending shaft. The shaft is rigidly mounted at itsupper end to an upper portion of the outer column and extends axiallydownwardly within the two telescoping columns. An intermediate portionof the depending loop of the cable is rigidly attached to the lowerinner column so that telescoping movement of the outer column eitherupwardly or downwardly is possible only when the spool is free torotate. Thus, since the clutch spring permits rotation of the drum inone direction without an overt release of tension, the cable isdirectionally wound around the spool with respect to the attachment ofthe intermediate portion of the depending cable loop to the inner columnso that the upper outer column can be raised without overtly releasingthe tension on the clutch spring. However, since the spool is not freeto rotate in the opposite direction unless the clutch spring tension isovertly released, the table cannot be lowered unless the clutch springtension is so released.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of anoverbed table constructed according to the present invention;

FIG. 2 is an end elevation view of the overbed table of FIG. 1;

FIG. 3 is an exploded perspective view of the pedestal column assemblyof the overbed table of FIG. 1;

FIG. 4 is a perspective view of the clutch assembly of the overbed tableof FIG. 1;

FIG. 5 is an end elevation view of the clutch assembly of FIG. 4 showingthe override assembly thereof;

FIG. 6 is an exploded perspective view of the clutch, override, cableand constant force spring assembly components of the overbed table ofFIG. 1;

FIG. 7 is a plan view of the clutch and override assembly of the overbedtable of FIG. 1;

FIG. 8 is a cross-sectional view of the pedestal of the overbed table ofFIG. 1 taken along the plane VIII- -VIII of FIG. 1;

FIG. 9 is a fragmentary end elevational view of the actuator lever armassembly on the pedestal of the overbed table of FIG. 1;

FIG. 10 is a cross-sectional view taken along the plane X-X of FIG. 2;

FIG. 11 is a cross-sectional view of the pedestal of the overbed tableof FIG. 1 taken along the plane XlXl of FIG. 2; and

FIG. 12 is a fragmentary. perspective view of the mechanism utilized tolock the cable to the inner column.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings inmore detail, FIGS. 1 and 2 are respectively perspective and endelevational views of the overbed table of the present invention whichincludes table top 10, base 11, and pedestal 20. Table top is rigidlyattached to a metal tubular horizontal frame 12 which is welded orotherwise rigidly affixed to the top of the pedestal 20.

Pedestal includes an upper, outer column 21 which telescopes over alower inner column 22 which is rigidly connected at its lower end tobase 11. A pair of lever arms 40 and 41 are pivotally connected at theupper portion of outer column 21 and extend outwardly in oppositedirections. The end handles 42 and 43, which are affixed normally toarms 40 and 41, respectively, are accessible at the sides of table top10. Lever arms 40 and 41 are depressible to permit lowering of table top10 when desired, as will be explained more fully hereinafter. Byproviding a lever arm at each side of the table top 10, it will beappreciated that table top 10 can be placed over a patient from eitherside and in either case a lever arm will be accessible to both thepatient and to the nurse.

Referring now to FIG. 3, the telescoping of outer column 21 over innercolumn 22 is controlled by means of an internal lift assembly 23. Liftassembly 23 includes clutch assembly 50 and override assembly 80 mountedon mounting bracket 24 which has side flanges 25 for rigidly mountingthe lift assembly to the upper inside portion of upper column 21 throughbolt holes 26. Depending from mounting bracket 24 is a rigid member 27which is slightly longer than the length of outer column 21. The lowerend of member 27 is provided with a horizontal foot portion having arubber bumper 28 which limits the telescoping travel of the outer columnin both up and down directions. It contacts the bottom wall of innercolumn 22 when outer column 21 is telescoped downwardly over innercolumn 22 to the fullest extent. It contacts the arrest bracket 122 whenouter column 21 is at the limit of its upward reach.

Toward the lower end of member 27, one end of each of a pair of rolledconstant force leaf springs 29 is attached to opposite sides of member27. The other end of each of the constant force springs is attached torotatable spindles 30 which extend outwardly from the rolled constantforce leaf spring sufficient to be seated in corresponding slots 31 inthe top portion of inner column 22. The spindle sections 30' are moldedfrom plastic and the bore thereof has a thin depressible circumferentiallip molded about the interior at 30". These lips 30" depress radiallyoutwardly when the spindle sections 30' are forced over the axles,returning to their initial configuration in the central, reduceddiametergroove in the axle. These lips retain the assemblies as an integral unitonce they have been assembled.

The adjacent faces of spool sections 30' come into abutment or nearabutment during assembly. The spool sections roll on axles 30, the axlesbeing held stationary by the squared lugs on their extremities which fitinto and mate in non-rotatable fashion with slots 31 in inner column 22.

A pulley wheel 32 is positioned near the lower end of member 22. Thedepending loop of cable 59 is looped about this wheel as will beexplained more fully hereinafter.

To avoid frictional drag when outer column 21 is telescoped over innercolumn 22, a pair of rollers 33 is provided on each side of the upperportion of inner column 22. The axes of rollers 33 are offset withrespect to the minor width of column 22 and/or the rollers are slightlyundersized so that as column 21 is raised or lowered telescopically overcolumn 22, rollers 33 will bear the sliding movement between one insidesurface of outer column 21 and the adjacent outside surface of innercolumn 22. The contact between rollers 33 and the inside surface ofouter column 21 is more clearly shown in FIG. 10.

Referring now to FIGS. 47, the detailed construction of the clutch andoverride assemblies is shown. Clutch assembly includes a rotatable drumhorizontally rotatably mounted on mounting bracket 24 on axle 51. Therotatable drum consists of a clutch drum section 52 and an adjacentspool section 53. Although a single-piece rotatable drum can beemployed, in the preferred embodiment, as shown in FIG. 6, spool section53 consists ofa pair of spool halves 54 and 55 each of which has a setof ratchet teeth 56 and 57, respective, on the inner, stepped-downdiameter axial face thereof. Teeth 56 and 57 mesh and lock together inthe working direction when the spool halves are brought together tointerlock the two spool halves so that they rotate together as a singlespool. The ratchet teeth permit relative rotation of the spool halves inthe nonworking direction such that cable 59 can be wound into workingposition during assembly of the mechanism by merely turning splined face63', and thus spool half 53, with a conventional open-end wrenchcounterclockwise as viewed in FIG. 6. The inner axle extensions of spoolhalves 54 and 55 are preferably interlocked axially through a spool hub58 to avoid any fouling of cable 59 when wound around the spool.Cableretaining slots 60 and 61 are provided in the periphery of spoolhalves 54 and 55, respectively, in which the two ends of cable 59 aresecured, as will be more fully explained hereinafter.

Clutch drum 52 is bored centrally and includes a series of notches 62spaced at intervals around the inside wall of the bore. Notches 62receive corresponding radial splines 63 on the outer stepped-downdiameter axial extension 64 of spool half 54 so that clutch drum 52 isrotated whenever spool portion 54 is rotated. It will be noted thatspool half 55 also has an outer axial extension with a plurality ofradial splines 63'. This intelligence is functional not only duringassembly of the device but permits spool halves 54 and 55 to beidentical, thus simplifying manufacturing.

Ratchet faces 56 and 57 are resiliently forced together by means of aspring washer 34 sandwiched within bracket 24. Shaft 51, retainedagainst bracket 24 at one end by trip plate 81, is grooved at itsopposite extremity to receive a snap ring 35 to retain the clutchassembly together. Stepped-down section 64 of spool half 54 is axiallyelongated with respect to clutch drum 52 and, when fabricated frommolded plastic as in the preferred form of this invention, serves as athrust bearing against the interior sidewall of bracket 24.

The base of bracket 24 has two slots formed therein I through whichcable 59 passes from opposite sides of spool 53. A U-shaped spring clipclosely enveloping the side portions of the cable drum, is snapped intothe opposed exterior edges of these slots and insures proper take-up andrelease of cable 59 by spool assembly.

A peripheral helically coiled clutch spring 65 having ends 66 and 67 isprovided around clutch drum 52. End 66 is formed to extend generallyhorizontally and is retained against upward movement by upperfinger-like extension 71 of trip plate 70 as is discussed more fullybelow. However, end 66 is free to move downwardly. End 67 is formed toextend vertically downward and is retained against movement to the left(FIG. 5) by the lower horizontal foot 82 of the spring-biased trip plate81 of override assembly 80 as will be discussed hereinafter. End 67 isretained from movement to the right, as viewed in FIG. 5, by itsabutment with edge 83 of aperture 83.

Beginning at end 66, clutch spring 65 is coiled clockwise in thedirection of end 67. Clutch spring 65 is tensioned and sized so thatclutch drum 52 cannot be rotated in the direction of arrow A in FIGS. 4and 6 because of the coil tightening and gripping effect when clutchdrum 52 is rotatably urged in that direction and the retention of end 67against foot 82. However, when clutch drum 52 is rotated in the oppositedirection, end 66 is free to move downwardly while end 67 is fixed dueto its abutment with wall 83'. This slightly uncoils clutch spring 65 sothat no coil tightening and gripping effect is produced. Therefore,clutch drum 52 can be rotated within clutch spring 65 in a directionopposite to arrow A.

Referring to FIGS. 4, 8 and 11, the function of cable 59 is most clearlyshown with table top 10 being almost at its lowest position in FIGS. 8and 11 with constant force springs 29 nearly completely unrolled. Asshown in FIG. 4, each end of cable 59 is provided with an anchoring orlocking bead 68 and 69 which is received in cable slots 60 and 61,respectively, of the spool halves 54 and 55. Starting from locking bead69, cable 59 is wound in one direction around spool portion 54, andstarting from locking bead 68, cable 59 is wound around spool portion 55in the opposite direction until a depending loop remains which is justlong enough to be received around pulley 32 at the lower end of shaft27. This winding can be easily accomplished, as noted previously, byfree-wheeling spool half 53 counterclockwise as shown in FIG. 6. Thisprocedure is continued until the depending loop is tensioned aroundpulley 32. Final tightening can be accomplished by placing an end wrenchinto engagement with splines 63'. Ratchet faces 56 and 57, resilientlyurged together by washer 34, will thereafter prevent unwinding of thecable except when an equal amount is wound up on the opposite side ofspool 53.

One of the features of the overbed table disclosed herein resides in theability to assemble the components illustrated in FIG. 6 as an integralunit prior to insertion of the same into column 22. The constant forcesprings, clutch assembly, overload protection means, cable dependingloop portion; and all other internal mechanism employed in the counterbalance and height control, more particularly, is constructed as aseparate, removable lift assembly and is removed and serviced as a totalunit. Because trip plate 70, to be discussed hereinafter, is part of theouter column assembly, and because finger-like extension engages clutchspring 65 above the horizontal end 66, when the two bolts 26 are removedthe entire outer column assembly with lever arms and trip plate intactmay be removed to give access to the lift assembly as a unit.

Once such assembly has been completed, the unit may be easily insertedinto the lower column by merely wedging foot 28 under arrest bracket122, seating the axles of constant force spring spindles into slots 31and thereafter bolting the upper column 21 to the bracket 24 viaapertures 26 on flanges 25. During this assembly process, the one pointon cable 59 is fixedly attached to the upper extremity of inner column22.

To this end, an intermediate lug 101 is provided on cable 59. This lugis engaged by a bifurcated retaining clip 102 having a planar section103 containing a screw vaperture 104, a rearwardly projecting bifurcatedsection 105, and a forwardly curved bifurcated section 106. Once theassembly shown in FIG. 6 is inserted into the inner column 22, thebifurcated sections of clip 102 are protruded into opening 107 and lug101 engaged in the manner shown in FIG. 12. Clip 102 is then secured inthe position shown in FIG. 10 by means of a screw, bolt or the like.Sufficient clearance is provided between the inner and outer columns sothat the presence of clip 102 and its attachment screw does notinterfere with smooth telescoping of the inner and outer columns.

With point 101 of cable 59 fixed with respect to inner column 22 in thismanner, the only way that outer column 21 can be moved upwardly ordownwardly is for spool portion 53 to rotate and unwind or pay out aportion of cable 59 from one side while taking up an equal portion fromthe other side. Therefore, when clutch spring 65 is tensioned, clutchdrum 52 and consequently spool portion 53 will not be able to rotate inthe direction of arrow A and accordingly upper column 21 cannot betelescoped downwardly over column 22. However, since clutch drum 52 canbe rotated in the direction opposite arrow A, because of the uncoilingeffect permitted by end 66 of clutch spring 65, outer column 21 can beraised upwardly since spool portion 53 will be free to rotate to pay outand take up an equal amount of cable 59.

To release the tension of clutch spring 65 on clutch drum 52 so thatspool portion 53 will be free to rotate in the direction of arrow A tolower the table top, either a downward force is exerted on end 66 ofclutch spring 65 tending to unwind clutch spring 65 or end 67 ispermitted to move to the left (FIG. 5) by override assembly 80 so thatno gripping action will result when clutch drum 52 is rotatably urged inthe direction of arrow A. To relieve the tension of clutch spring 65 onclutch drum 52 by a downward force acting on clutch spring end 66, avertically reciprocable trip plate 70 (FIGS. 7, 9 and 11) is mountedadjacent the upper outer side of outer column 21. Trip plate 70 has afinger-like extension 71 which extends through an elongated slot 72 inouter column 21 to be in depressing engagement with horizontal end 66 ofclutch spring 65. Trip plate 70 also has a lower finger-like extension74 to engage lever arms 40 and 41 as explained hereinafter.

Lever arms 40 and 41 are pivotally connected at the upper portion ofouter column 21 by means of a pivot bolt 44 passing through the end oflever arm 40 into outer column 21 and by a pivot bolt 45 passing throughthe end of lever arm 41 into outer column 21. Lever arms 40 and 41 aremounted so that the ends thereof overlap. Bolt 44 also passes through avertically elongated aperture 46 in lever arm 41 and bolt 45 passesthrough a vertically elongated aperture 47 in lever arm 40 to controlthe degree of pivoting of the lever arms about their pivot points. Aspring 48 interconnects depending ears provided on lever arms 40 and 41to bias the lever arms in their full upper position (FIG. 9). Thus, whenthe lever arms are depressed to the fullest extent permitted byelongated apertures 46 or 47 and then released, they will beautomatically returned to their upper position.

At the lower end of trip plate 70, an outwardly extending finger 74extends through overlying apertures 49 through lever arms 40 and 41.Thus, when either of the lever arm handles are depressed, trip plate 70will be moved downwardly to depressing end 66 of spring 65 to produce aspring uncoiling effect which releases the tension thereof on clutchdrum 52. As long as one of the lever arm handles is kept depressed tomaintain the released clutch spring tension on clutch drum 52, the tabletop can be lowered by a slight downward force since spool 53 will befree to rotate in the direction of arrow A to pay out and take-upcorresponding amounts of cable 59. Generally, the downward force exertedon the lever arm handle is sufficient to provide the necessary downwardforce needed to overcome the upward biasing force of constant forcespring 29 to achieve downward movement for telescoping of outer column21 over inner column 22. As soon as the lever arm is released, springmeans 48 will cause it to automatically return to its fullest upperposition thereby raising trip plate 70 and end 66 of spring 65 resultingin tension again being placed on clutch drum 52 by clutch spring 65.Thus, a positive continued downward force is required on one of thelever arms to maintain a downward movement of the table top, andconsequently, there is no possibility of the table top being loweredfaster than desired since as soon as downward force exertion by theoperator on the lever arm ceases, the table will cease its loweringaction. Cessation of the downward force will occur whenever the tabletop catches up to the operators hand thus insuring that the table topwill not lower further or more quickly than desired.

Table top can also be lowered without depressing one of the lever armsby exerting a large downward force directly on the table top such asmight be experienced if someone were to fall upon it. The primaryfunction of this feature is to prevent damage to the table in such aloading situation. This is accomplished by means of override assembly 80which is most clearly shown in H6. 5.

Override assembly 80 includes spring-biased override lever 81 which isrotatably mounted on mounting bracket 24 at one end of axle 51. Lever 81has a lower horizontal foot portion 82 which extends through an opening83 in the sidewall of mounting bracket 24 to contact vertical end 67 ofclutch spring 65. A spring means such as coil spring 85 extends betweenthe top portion of side flange 25 and atop outwardly extendinghorizontal extension 84 on lever 81 to bias foot 82 against edge 83" ofopening 83. By this arrangement, when a large downward force is exertedon the table top in the direction of arrow A clutch drum 52 will berotatably urged with sufficient force to overcome the tension ofoverride spring 85. Lever 81 will then rotate slightly in a clockwisedirection (FIG. 5) permitting movement of spring end 67 to the left(FIG. 5) and permitting spring end 66 to engage fingerlike extension 71of trip plate to release the tension of clutch spring 65 on clutch drum52. As long as this requisite downward force is maintained, spool 53will be free to rotate in the direction of arrow A and table top 10 canbe lowered. However, as with the action of the lever arm, when thedownward force on the table top 10 is discontinued or diminished to'suchan extent that the force of spring means 85 is no longer overcome andoverride lever 81 rotates back to the original position thereby againplacing clutch spring 65 under tension, the downward movement of tabletop 10 will stop. The spring constant of spring 85 should be chosen, aswill be readily apparent to those skilled in the art, such that overridelever 81 will be permitted to rotate only when the table top experiencesan atypical loading.

it will be apparent to those skilled in the art from a reading of theforegoing specification and study of the accompanying drawings that thisinvention has provided a novel and unobvious vertically adjustableoverbed table. The table may be raised merely by exerting an upwardforce thereagainst. Once it has been raised to a predetermined position,it will be locked from downward movement by action of the unique clutchassembly. The table may be lowered from this position only by theactuation of the override assembly in an atypical loading situation orby depression of the clutch lever arms. There is no danger, during suchdownward movement, of the table top running away downwardly since aconstant downward force must be maintained either on the table top orthe lever arms for continued downward movement.

While a preferred embodiment of the present invention has been describedand illustrated, it will be understood to those skilled in the art thatchanges and modifications can be made without departing from the spiritof the invention. Accordingly, the scope of the present invention isdeemed to be limited only by the following appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A vertically adjustable overbed table comprising:

a pedestal, a horizontal table top mounted at the top of said pedestaland a base platform at the lower end of said pedestal;

said pedestal including an outer column and an inner column, said outercolumn telescopically engaging said inner column and being adapted forvertical telescoping movement with respect to said inner column; atleast one spring means associated with said columns for maintaining thetelescoping movement of said outer column and said inner column inapproximate equilibrium; and a clutch assembly mounted within saidpedestal;

said clutch assembly including a rotatable clutch drum, means forrotating said drum during telescopic movement of said columns, atensioned clutch spring means surrounding said drum for permittingupward movement'of one of said columns with respect to the other of saidcolumns when an upward force is exerted thereon sufficient to overcomethe equilibrium effect of said constant force spring and for permittingdownward movement of said one column with respect to said other columnonly when the tension of said clutch springis released; and means forreleasing the tension of said clutch spring.

2. The overbed table according to claim 1 wherein said outer columnisaffixed to said table top, wherein said inner column is affixed tosaid base and wherein said clutch assembly is mounted within said outercolumn and comprises a horizontally mounted rotatable clutch drum; atensioned helical coil spring around said drum; a horizontally mountedrotatable cable spool adjacent said clutch drum and connected thereto soas to be rotatable therewith and only therewith; a cable having its endswound around said spool in opposite directions, the ends of said cablebeing affixed to said spool and an intermediate portion of said cableextending below said spool to form a depending cable loop and anintermediate point of said cable loop being affixed to said innercolumn; a rigid member depending within said columns and attached at itsupper end to an upper portion of said outer column and having a pulleywheel at the lower end thereof receiving said depending cable loop,whereby said outer column can be telescoped downwardly over said innercolumn when a downward force is placed on said outer column only whensaid clutch spring tension is released and said spool is free to rotateto take up cable above said intermediate point of said depending cableloop and to pay out an equal amount of cable below said intermediatepoint of said depending cable loop.

3. The overbed table according to claim 2 wherein one end of said clutchspring extends outwardly from said spring coil and wherein said meansfor releasing the tension on said clutch spring comprises a trip platereciprocally mounted on said outer column; said trip plate having afinger-like extension in engagement with said one end of said clutchspring so that when said trip plate is moved in a first direction saidclutch spring tension is released so said table top can be lowered.

4. The overbed table according to claim 3 wherein at least one upwardlyspring-biased lever arm is pivotally mounted on said outer columnadjacent said trip plate and in engagement therewith so that when saidlever arm is depressed downwardly said trip plate will release theclutch spring tension.

5. The overbed table according to claim 4 which includes a pair of saidlever arms each extending outwardly from said outer column to oppositesides of said table top.

6. The overbed table of claim 4 wherein said spring means includes apair of said constant force springs; each of said constant force springscomprising a leaf spring rolled around an axle, each said constant forcespring having one end affixed to the lower end of said rigid member andhaving its axle horizontally rotatably mounted at an upper portion ofsaid inner column.

7. The overbed table according to claim 6 which further comprises aspring-biased override assembly mounted on said outer column adjacentsaid clutch assembly in engagement with the other end of said clutchspring whereby when a downward force is exerted on said outercolumnsufficient to overcome the spring biasing of said overrideassembly, said override assembly will release the clutch spring tensionso that said table top can be lowered.

8. The overbed table of claim 7 wherein movement of said one end of saidclutch spring is in a direction opposite to said first direction isrestricted by said fingerlike extension, wherein the other end of saidclutch spring depends away from said clutch spring coil and wherein saidoverride assembly comprises an override lever rotatably mounted adjacentsaid other end of said clutch spring having a foot in engagement withsaid other end of said clutch spring; said override lever being springbiased against rotation in a direction in which said foot will tend tobe moved by said other end of said clutch spring when a downward forceis exerted on said outer column whereby when a downward force is exertedon said outer column sufficient to overcome the spring-biasing of saidoverride lever. said override lever will be rotated by said other end ofsaid clutch spring and the clutch spring tension will thereby bereleased to permit said table top to be lowered.

9. The table as set forth in claim 2 wherein said spool includes twoabutting sections, one section being rotatable with respect to the otherto wind cable thereon during assembly of said table.

10. The table as set forth in claim 9 wherein said spool sections haveratchet faces in abutment with one another permitting one section to berotated with respect to the other in a non-working direction only towind cable thereon during assembly of said table.

11. The table as set forth in claim 10 which further comprises means forresiliently urging said faces together.

12. A vertically adjustable overbed table comprising:

a pedestal, a horizontal table top mounted at the top of said pedestaland a base platform at the lower end of said pedestal;

said pedestal including an outer column and an inner column, said outercolumn telescopically engaging said inner column and being adapted forvertical telescoping movement with respect to said inner column; and aclutch assembly mounted within said pedestal for controlling thetelescoping movement of said columns;

said clutch assembly including a rotatable clutch drum, means forrotating said drum during telescopic movement of said columns, atensioned clutch spring means for selectively restraining rotation ofsaid drum, said spring means permitting free rotation of said drum in afirst direction to permit free upward movement of one of said columnswith respect to the other of said columns when an upward force isexerted thereon, said spring means restraining rotation of said drum ina direction opposite to said first direction to restrain downwardmovement of said one column with respect to said other column; and meansfor releasing the tension on said clutch spring to permit free rotationof said drum in said opposite direction.

13. The overbed table according to claim 12 wherein said outer column isaffixed to said table top, wherein said inner column is affixed to saidbase and wherein said clutch assembly is mounted within said outercolumn and comprises a horizontally mounted rotatable clutch drum; atensioned helically coiled spring positioned around said drum, saidspring having one end thereof arrested from movement and beingpositioned around said drum such that the spring tends to tightenradially under the influence of attempted rotation of said drum in saidopposite direction, a horizontally 1 I mounted rotatable cable spooladjacent said clutch drum and connected thereto so as to be rotatabletherewith'and only therewith; a cable having its ends wound around saidspool in opposite directions, the ends of said cable being affixed tosaid spool and an intermediate portion of said cable extending belowsaid spool to form a depending cable loop and an intermediate point ofsaid cable loop being affixed to said inner column; a rigid memberdepending within said columns and attached' at its upper end to an upperportion of said outer column and having a pulley wheel at the lower endthereof receiving said depending cable loop,

downwardly to release the tension of said clutch spring.

1. A vertically adjustable overbed table comprising: a pedestal, ahorizontal table top mounted at the top of said pedestal and a baseplatform at the lower end of said pedestal; said pedestal including anouter column and an inner column, said outer column telescopicallyengaging said inner column and being adapted for vertical telescopingmovement with respect to said inner column; at least one spring meansassociated with said columns for maintaining the telescoping movement ofsaid outer column and said inner column in approximate equilibrium; anda clutch assembly mounted within said pedestal; said clutch assemblyincluding a rotatable clutch drum, means for rotating said drum duringtelescopic movement of said columns, a tensioned clutch spring meanssurrounding said drum for permitting upward movement of one of saidcolumns with respect to the other of said columns when an upward forceis exerted thereon sufficient to overcome the equilibrium effect of saidconstant force spring and for permitting downward movement of said onecolumn with respect to said other column only when the tension of saidclutch spring is released; and means for releasing the tension of saidclutch spring.
 2. The overbed table according to claim 1 wherein saidouter column is affixed to said table top, wherein said inner column isaffixed to said base and wherein said clutch assembly is mounted withinsaid outer column and comprises a horizontally mounted rotatable clutchdrum; a tensioned helical coil spring around said drum; a horizontallymounted rotatable cable spool adjacent said clutch drum and connectedthereto so as to be rotatable therewith and only therewith; a cablehaving its ends wound around said spool in opposite directions, the endsof said cable being affixed to said spool and an intermediate portion ofsaid cable extending below said spool to form a depending cable loop andan intermediate point of said cable loop being affixed to said innercolumn; a rigid member depending within said columns and attached at itsupper end to an upper portion of said outer column and having a pulleywheel at the lower end thereof receiving said depending cable loop,whereby said outer column can be telescoped downwardly over said innercolumn when a downward force is placed on said outer column only whensaid clutch spring tension is released and said spool is free to rotateto take up cable above said intermediate point of said depending cableloop and to pay out an equal amount of cable below said intermediatepoint of said depending cable loop.
 3. The overbed table according toclaim 2 wherein one end of said clutch spring extends outwardly fromsaid spring coil and wherein said means for releasing the tension onsaid clutch spring comprises a trip plate reciprocally mounted on saidouter column; said trip plate having a finger-like extension inengagement with said one end of said clutch spring so that when saidtrip plate is moved in a first direction said clutch spring tension isreleased so said table top can be lowered.
 4. The overbed tableaccording to claim 3 wherein at least one upwardly spring-biased leverarm is pivotally mounted on said outer column adjacent said trip plateand in engagement therewith so that when said lever arm is depresseddownwardly said trip plate will release the clutch spring tension. 5.The overbed table according to claim 4 which includes a pair of saidlEver arms each extending outwardly from said outer column to oppositesides of said table top.
 6. The overbed table of claim 4 wherein saidspring means includes a pair of said constant force springs; each ofsaid constant force springs comprising a leaf spring rolled around anaxle, each said constant force spring having one end affixed to thelower end of said rigid member and having its axle horizontallyrotatably mounted at an upper portion of said inner column.
 7. Theoverbed table according to claim 6 which further comprises aspring-biased override assembly mounted on said outer column adjacentsaid clutch assembly in engagement with the other end of said clutchspring whereby when a downward force is exerted on said outer columnsufficient to overcome the spring biasing of said override assembly,said override assembly will release the clutch spring tension so thatsaid table top can be lowered.
 8. The overbed table of claim 7 whereinmovement of said one end of said clutch spring is in a directionopposite to said first direction is restricted by said finger-likeextension, wherein the other end of said clutch spring depends away fromsaid clutch spring coil and wherein said override assembly comprises anoverride lever rotatably mounted adjacent said other end of said clutchspring having a foot in engagement with said other end of said clutchspring; said override lever being spring biased against rotation in adirection in which said foot will tend to be moved by said other end ofsaid clutch spring when a downward force is exerted on said outer columnwhereby when a downward force is exerted on said outer column sufficientto overcome the spring-biasing of said override lever, said overridelever will be rotated by said other end of said clutch spring and theclutch spring tension will thereby be released to permit said table topto be lowered.
 9. The table as set forth in claim 2 wherein said spoolincludes two abutting sections, one section being rotatable with respectto the other to wind cable thereon during assembly of said table. 10.The table as set forth in claim 9 wherein said spool sections haveratchet faces in abutment with one another permitting one section to berotated with respect to the other in a non-working direction only towind cable thereon during assembly of said table.
 11. The table as setforth in claim 10 which further comprises means for resiliently urgingsaid faces together.
 12. A vertically adjustable overbed tablecomprising: a pedestal, a horizontal table top mounted at the top ofsaid pedestal and a base platform at the lower end of said pedestal;said pedestal including an outer column and an inner column, said outercolumn telescopically engaging said inner column and being adapted forvertical telescoping movement with respect to said inner column; and aclutch assembly mounted within said pedestal for controlling thetelescoping movement of said columns; said clutch assembly including arotatable clutch drum, means for rotating said drum during telescopicmovement of said columns, a tensioned clutch spring means forselectively restraining rotation of said drum, said spring meanspermitting free rotation of said drum in a first direction to permitfree upward movement of one of said columns with respect to the other ofsaid columns when an upward force is exerted thereon, said spring meansrestraining rotation of said drum in a direction opposite to said firstdirection to restrain downward movement of said one column with respectto said other column; and means for releasing the tension on said clutchspring to permit free rotation of said drum in said opposite direction.13. The overbed table according to claim 12 wherein said outer column isaffixed to said table top, wherein said inner column is affixed to saidbase and wherein said clutch assembly is mounted within said outercolumn and comprises a horizontally mounted rotatable clutch drum; atensioned helically coiled spring positIoned around said drum, saidspring having one end thereof arrested from movement and beingpositioned around said drum such that the spring tends to tightenradially under the influence of attempted rotation of said drum in saidopposite direction, a horizontally mounted rotatable cable spooladjacent said clutch drum and connected thereto so as to be rotatabletherewith and only therewith; a cable having its ends wound around saidspool in opposite directions, the ends of said cable being affixed tosaid spool and an intermediate portion of said cable extending belowsaid spool to form a depending cable loop and an intermediate point ofsaid cable loop being affixed to said inner column; a rigid memberdepending within said columns and attached at its upper end to an upperportion of said outer column and having a pulley wheel at the lower endthereof receiving said depending cable loop, whereby said outer columncan be telescoped downwardly over said inner column when a downwardforce is placed on said outer column only when said clutch springtension is released and said spool is free to rotate to take up cableabove said intermediate point of said depending cable loop and to payout an equal amount of cable below said intermediate point of saiddepending cable loop.
 14. The table as set forth in claim 12 whereinsaid releasing means comprises a lever which is moveable downwardly torelease the tension of said clutch spring.